JP2000202843A - Apparatus for manufacture of film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a film which is improved in an irregularity of a thickness by enabling a slit clearance to be highly precisely and finely adjusted by a method wherein a slit clearance for extruding a solution film in a mouthpiece is formed by a pair of lips, and heat bolt is used for one side of slit clearance-adjusting means at both lips. SOLUTION: A solution film 3 is cast on a transfer cast face 4 from a slit clearance 2 of a mouthpiece 1. The slit clearance 2 is formed between a pair of lips 5a, 5b arranged opposed to each other. Further, a manual bolt 6 for adjusting the slit clearance 2 by displacing the lip 5b is provided in one side lip 5b. Furthermore, a heat bolt 8 which is expanded or contracted by radiation of heat from a built-in heating element 7 is arranged in the other lip 5a. Then, a thickness of the film is measured with a thickness meter, and an electric power or the like of the heating element 7 is controlled by a controller based on the measured result. Thereby, the heat bolt 8 is elongated or contracted, and the slit clearance 2 is expanded or contracted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film manufacturing apparatus for casting a solution film obtained by dissolving a resin in a solvent or a solution to form a film.

[0002]

2. Description of the Related Art There is known a method in which a solution resin is extruded into a sheet form from a slit gap of a die, cast on a moving cast surface, and formed into a resin film through a drying step or the like. In such a film manufacturing apparatus, the thickness and the thickness unevenness of the film to be formed are adjusted by first adjusting the slit gap of the die. The slit gap is formed by a pair of lips facing each other. In a conventional die used for solution casting, at least one lip is mechanically adjusted by adjusting bolts arranged in a plurality in the die width direction. Has been adopted. Since this adjustment is performed manually, there is a limit to the accuracy of adjusting the thickness and thickness unevenness of the finally formed film.

In a film manufacturing apparatus in which a resin is melted and a molten resin film is extruded from a die into a sheet shape, a heat bolt utilizing the expansion and contraction of a bolt due to heat radiation of a heating element is used to more precisely adjust the film thickness. Is known (for example, Japanese Patent Publication No. 6-2889).
No. 1), and no example using such a base is found in solution casting.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the structure of a die in a solution casting method, thereby enabling more precise fine adjustment of a slit gap, and ultimately, a higher precision. To produce a film having a high thickness and improved thickness unevenness.

[0005]

In order to solve the above-mentioned problems, a film manufacturing apparatus according to the present invention is directed to a film manufacturing apparatus for casting a solution film extruded from a slit gap of a die onto a moving casting surface. The base is
A pair of lips provided to face each other to form the slit gap, and adjusting means for adjusting the slit gap provided on each lip, at least one of the adjusting means is provided by heat radiation of a heating element. It is a heat bolt utilizing the expansion and contraction of the bolt.

The film manufacturing apparatus preferably further comprises a thickness adjusting means for controlling the power applied to the heat bolt or the on-rate of the heating element based on thickness data of the solution film after molding.

Further, it is preferable that the apparatus has a cover surrounding the heat bolt, means for supplying gas into the cover, and means for discharging gas supplied into the cover.

In such a film manufacturing apparatus,
The slit gap of the base can be adjusted by using expansion and contraction of the heat bolt. The expansion and contraction of the heat bolt is caused by the heat radiation of the heating element. Since the heating element can control the amount of heat radiation freely and with extremely high precision by controlling the power or ON rate, the expansion and contraction amount of the heat bolt is extremely small. Fine adjustment can be made with high accuracy, and the slit gap is adjusted to a desired state with high accuracy.

Therefore, if the heat bolt is controlled by feeding back the thickness information of the formed film,
Thickness accuracy and thickness unevenness of the finally formed film are remarkably improved.

One of the reasons why such an automatically controlled base using a heat bolt was not used for solution casting is as follows.
It is considered that the solvent is scattered around the base in the solution casting, which may have an adverse effect such as disabling the operation of the heat bolt and the like and making explosion proof difficult due to the use of electric components such as a heating element. However, by providing a cover so as to surround the heat bolt and purging the inside of the cover with a gas, for example, air, the above-mentioned fear is completely removed. Further, by surrounding with a cover, the ambient temperature of the heat bolt can be equalized, and the accuracy of control using the heat bolt is further improved. Therefore, by adopting such a configuration, extremely high thickness control accuracy can be obtained while preventing inconvenience.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. 1 and 2
1 shows a film manufacturing apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a base,
The solution film 3 in which the resin is dissolved in the solvent or the solution is cast from the slit gap 2 on the moving cast surface 4.
The slit gap 2 is formed by a pair of lips 5 provided opposite to each other.
a, formed between 5b.

As for the one lip 5b, a manual bolt 6 for adjusting the slit gap 2 by manually displacing the lip 5b is provided as slit gap adjusting means as in the conventional apparatus. A predetermined number of manual bolts 6 are arranged in the width direction of the base 1, that is, in the direction perpendicular to the plane of the paper of FIG. The manual bolt 6 is for initially coarsely adjusting the slit gap 2.

The other lip 5a is provided with a heat bolt 8 which incorporates a heating element 7 and utilizes expansion and contraction of the bolt due to heat radiation of the heating element 7. For example, a cartridge heater is used as the heating element 7, and the amount of heat radiation, that is, the amount of heat for expanding and contracting the heat bolt 8 can be finely adjusted steplessly by controlling the power or the ON rate. The heat bolts 8 are also arranged in a predetermined number in the width direction of the base 1, that is, in a direction perpendicular to the paper surface of FIG. Extending the heat bolt 8 narrows the slit gap 2 at a position corresponding to the heat bolt 8, and contracting the heat bolt 8 expands the slit gap 2 at a position corresponding to the heat bolt 8.

The base 1 is provided with a cover 9 which covers the heat bolts 8 so as to surround the heat bolts 8. In the enclosed space 10, a gas supply pipe 11 as a gas supply means connected to the cover 9 is provided. Gas (for example, air) is supplied, and gas supplied into the space 10 is discharged from the opposite side from a gas discharge path 12 formed as a gas discharge unit in the base 1. That is, the gas in the space 10 is purged. This purging may be performed continuously or intermittently. It is preferable to purge the heat bolt 8 little by little so that the gas around the heat bolt 8 is not excessively cooled by the gas, so that the temperature fluctuation around the heat bolt 8 is suppressed. Further, since the gas flows in the space 10 little by little, the temperature in the space 10, that is, the atmosphere around the heat bolt 8 can be equalized.

As shown in FIG. 2, the casting surface 4 is formed by a circling belt 14 stretched between drums 13a and 13b in this embodiment. However,
The casting surface can also be formed by a single rotating drum. Reference numeral 15 in FIG. 2 denotes a suction chamber provided for stabilizing landing and close contact of the solution film 3 discharged from the base 1 on the casting surface 4. In the present embodiment, these devices are housed in an oven for drying and discharging the volatile solvent, and as a whole, the casting machine 1
6.

The sheet 18 peeled and formed from the peeling roll 17 in the casting machine 16 is stretched by a longitudinal stretching machine 19 in the longitudinal direction at a predetermined stretching ratio.
According to 0, the film is stretched at a predetermined stretching ratio in the width direction and is formed into a target biaxially stretched film 21.

The biaxially stretched film 21 is wound into a spool by a winder 22, and its thickness is measured by a thickness gauge 23 before winding. The thickness gauge 23 is scanned in the film width direction, and can measure thickness unevenness in the width direction as well as the thickness of the film 21 itself.
As the thickness gauge 23, a known gauge such as a β-ray thickness gauge can be used.

The thickness information detected by the thickness gauge 23 is sent to a control device 24, and based on a signal from the control device 24,
The power or the ON rate of the heating element 7 in the heat bolt 8 is controlled.

In this embodiment, the thickness gauge 23 is provided just before the winding machine 22. The thickness gauge 23 is provided immediately before the winding machine 22, so that the thickness of the product can be controlled easily. Since the position is far from 1, control may take a long time and responsiveness may decrease. In such a case, the casting machine 1
Another thickness gauge (not shown) can be installed immediately after the peeling roll 17 of FIG. When such a thickness gauge is installed, since there is a stretching step after that, the controllability of the product is reduced depending on the thickness gauge, but a high control response is obtained because the thickness gauge is close to the base 1. Therefore, thickness gauges may be installed at the above two locations, and the thickness information to be fed back may be switched as needed.

In the film manufacturing apparatus according to this embodiment having the above-described configuration, the slit 1
First, after coarse adjustment is performed with the manual bolt 6, fine adjustment is performed with the heat bolt 8. In the adjustment of the slit gap 2 by the heat bolt 8, the fine adjustment of the absolute value of the slit gap 2 and the fine distribution of the gap in the die width direction are also performed. The heat bolt 8 can be adjusted with high precision and steplessly as described above. The adjustment of the slit gap 2 by the heat bolt 8 is based on the thickness information fed back from the thickness gauge 23, and the controller 4 compares the adjusted thickness information with the set thickness information to calculate the correction control amount.
It is adjusted based on the control amount. Therefore, the thickness and thickness unevenness of the film to be formed are automatically and accurately controlled to a desired accuracy.

The installation portion of the heat bolt 8 is a cover 9.
In addition, since the atmosphere in the space 10 covered with the cover 9 is purged, the solvent evaporated from the solution film 3 is prevented from adhering to the heat bolt 8, and explosion-proof measures are sufficiently taken. Will be applied. Therefore, the fine adjustment function of the die slit gap 2 by the heat bolt 8 is stably maintained. In addition, this purge makes it possible to equalize the temperature around the heat bolt 8 as described above, and the accuracy of the slit gap fine adjustment by the heat bolt 8 is further improved.

Although the above embodiment has been described in connection with the case where the casting surface 4 is formed by the circling belt 14, the present invention can be applied to the case where the casting surface is formed by a rotating drum.

[0023]

As described above, according to the film manufacturing apparatus of the present invention, in the solution casting, particularly by improving the slit gap adjusting mechanism in the die, the slit gap can be formed with extremely high precision without causing any inconvenience. , And a film having good thickness accuracy and improved thickness unevenness can be manufactured.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view of a film manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic overall configuration diagram of the film manufacturing apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cap 2 Slit gap 3 Solution film 4 Cast surface 5a, 5b Lip 6 Manual bolt 7 Heating element 8 Heat bolt 9 Cover 10 Space 11 Gas supply pipe 12 Gas exhaust path 13a, 13b Drum 14 Belt 15 Suction chamber 16 Casting machine 17 Release roll 18 Sheet 19 Vertical stretching machine 20 Horizontal stretching machine 21 Biaxial stretching film 22 Winding machine 23 Thickness gauge 24 Controller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidetoshi Okagi 1-1-1, Sonoyama, Otsu-shi, Shiga F-term in the Shiga Plant of Toray Co., Ltd. (reference) 4F205 AC05 AG01 AJ11 AR12 GA07 GB02 GC07 GE01 GE06 GE22 GF01 GF06 GF23 GF24 GF47 GN24 GN27 GW21 4F207 AC05 AG01 AJ11 AM10 AR12 KA07 KJ09 KL42 KL76 KM15 KM20

Claims (3)

[Claims] 1. A film manufacturing apparatus for casting a solution film extruded from a slit gap of a base onto a moving casting surface, wherein the base comprises a pair of lips provided to face each other to form the slit gap. And an adjusting means for adjusting the slit gap provided in each lip, wherein at least one of the adjusting means is a heat bolt utilizing expansion and contraction of the bolt due to heat radiation of the heating element. apparatus. 2. The film according to claim 1, further comprising a thickness adjusting means for controlling the power applied to the heat bolt or the on-rate of the heating element based on thickness data of the formed solution film. manufacturing device. 3. The apparatus according to claim 1, further comprising a cover surrounding the heat bolt, a unit for supplying gas into the cover, and a unit for discharging gas supplied into the cover. The film manufacturing apparatus according to the above.